Process of cutting worm-gears.



A. BENSON. PROCESS 0F CUTTING WORM GEARS.

APPLIOATON FILED FEB. 3,1913l Patented Man-9,1915.

ANDREW BENSON, F CHICAGO, ILLINOIS, ASSIG'NOR T0 BENSON COMP' CHIQAGO, ILLINOIS, A` CORPORATION, 0F ILLINOIS.

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To all wtom z't'mai/ concern:

Be it known that l, ANDREW Benson, a

citizen of the United States, residing in Chicago, in the county of Cook and State oit Illinois, have invented a new and useful lmproyenent in Processes of Cutting @Worm- Gears, of which the following isa specifica tion.

This invention relates to. improvements in the process or cutting worm-gears, and

more particularly to the process of cutting teeth of worm-gears such as are used with worms ot the type commonly known asi the l-lindley screw; thatis, a worin of such "form that if anyl plane be taken through its longitudinal axis, the intersections of the of Worm-gears of any size, having any numt ber of teeth and of any desired pitch.

The invention furthermore consists in the improvements in the steps and novel combinations of the steps ot the process, as herein shown, described or claimed.

-He'retoiore, 'so far as ll ain aware, it has been the usual practice to cut wornrgears by means of a hob of the same form as the worm to be used with the Worin-gear, said hobbeing'provided with cutting edges or faces throughout 4the entire length of the thread of the hob. lin the case ot the ordinary worin and'worm-gea-r, that is, a worin having a constant diameter throughout its length, the formation ot a hob suitable for generating or'cutting `the worm-gear is a relatively simple matter, since thel cutting edges may be made by' cutting a plurality of straight slots through the threads of the heb at right angles to the slope oi the thread, which is, of course, constant. llVhen, however, a hob is to be formed suitable 'for cutting a worin-gear to be used with a worm of the Hindley screw' type, each cutting edge or point on the thread oi' the hob inust be formed independently, since the diameter of the thread of the hohis a constantly Specification-o Letters letent,

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ehaing'ing` one, and the' angle dit', the fades of the threadis likewise a coiistantly changing one, and in order to talte into vaccounat both of'the above named variable' elements and keep the cutting edges always at right angles to the slope of the thread, it is nejc-A essary to iiorin the cutting edges individbA 'necessarily separated, the teeth cut on the- Worm-gear will 'be more or less imperfect, with the result that the transmission oit ally, as above indicated. Such a hob i287 power from the worm to the worin-gear will be ineiicient. Another undesirable feature of the use o't'a hob of the type above indicatedvfor generating or cutting theworm-` gear teeth resides in the fact that as soon as' the cuttingedges become Worn to any ex- `tent, anew hob has to bernade, thus adding again to the cost of manufacture of worin gears.

'in cuttingthe teeth ot worm-gears by hobs under the old method, the faces of adjacent teeth are cut simultaneously and the nsame tooth is cut from both sides at the same time, the cuts ofcourse being made deeper and deeper as the cutting operation proceeds. l/Vith my process, however, l

proposeto cut the worm-gear teeth on one side only at a time, and tocut the same or corresponding sides or' Yfaces of all the teeth successively. With' my process, also', l propose to eutv oppositely disposed sides or faces of two non-consecutive.`teeth simultaneously and continue the cutting operation progressively until all the teeth are made of the desired form.

lin the drawing forming a part of this specification, Figure' 1 shows a mechanism suitable for carrying out my improved process. Figs. 2 and 3 are diagrammatic views illustrating two stages of the process of cutting the worm-gear teeth, and Fig. 4;

is a detail view illustrating a Hindley screw l2 of the 1n practice, theblank 10 will first be concaved on its periphery so that the finished worm-gear will properly fit the worm, and

the blank is then placed on a vertical arbor and clamped thereon and rotated thereby 1n the direction indicated by the arrow a inv Fig. 1, said arbor on which'the Vblank is mounted being driven by means of a wormgear 13 and worm 14 on a shaft 15, suitably mounted in a frame 16. The shaft is,l

driven by means ofa bevel gear (not shown) on the lower end of ak vertical shaft 17, the latter being in turn driven by means of a bevel gear 18, and bevel gear 19, on horizontal shaft 20, the llatter being driven from any suitablesource of power, not shown. Keyed to shaft ,and slidable thereon is a bevel gear 21, meshing with a bevel gear 22 adapted to drive a horizontal shaft 23 mounted in suitable bearings 24 on a. slide 25, mounted onguide-ways 26 on the top of the frame 16, said slide 25 being .moved lbackward and forward by means ofa handoperated swiveled adjusting screw 27. Mounted on the shaft or arbor 23k are two Sets of cutting tools 28 and 29, said toolsi 1 The number of the cutting ytools will depend upon'the number of threads on the worm and the amounts the tools 28 and 29 are angularly offset from each other will determine the thickness of the lfinished teeth in the worm-gear.

The operation is as follows: As will be understood, the blank from which the wormgear is'formed and the cutting tools will be continuously rotated in proper synchronism, and the cutting tools will be gradually andfp'rogressively fed toward the blank by means of the hand operated adjusting screw 27. vwWhen the blank is rotating in the direction indicated bythe arrow a, the cutting tools 28 will cut the forward or advancing sides or faces 31 of each successive tooth, and at the same time will begin to cut away lsome of the waste material 32 between the tooth being cut and the tooth in advance thereof. Simultaneously with the above described operation, 'the cutting tools 29 will begin to cut the rear or receding faces 33 of each successive tooth and will also begin Ato cut away, from the oppositeside, some of the waste material 32 between the tooth being operated upon and the next adjacent tooth. This operation is continued until all of the waste material between cach pair of teeth is cut away. As will be understood,

each tool of each of the sets 28 and 29 will engage one tooth only on the worm-gear during a complete rotation of the arbor supporting the tools.

Fromr the foregoing description, it will be seen that the teeth on the worm-gear will be accurately and uniformly cut, due to the fact that each cutting tool will move in a .path corresponding to the portion o fl the thread on the worm with which the wormygear beingcut is to be used, and which .its axis, simultaneously and synchronously cutting successive advancing faces only of the worm-gear teeth at one point of its eircumference and simultaneously and synchronously cutting successive receding faces only of other teeth .of the worm-gear at another point of its circumference, the cutters being rotated about an axis parallel to that of the worm with which the worm-gear is to coperate, Substantially as specified.

2. The process of cutting worm-gears for use with worms of the Hindlev screw type, which consists 'in rotating the blank in which the worm-gear is to be cut. and simultaneously progressively cutting the forward or advancing faces only of the teeth at one point, and cutting the rear or receding faces onlv of the teeth at another point, substan- 'tially as specified.

3. The process of cutting worm-gears, which consists in rotatingr the blank in which the worm-gear is to be cut. and at the same time cutting onlv all the sides of the teeth facing in one direction at one point. and cutting only all the sides of the teeth facing in the opposite direction at another point, substantially as specified. r

4. The process of cuttingworm-gears, which. consists in rotating the blank from which the wormgear is to be formed and simultaneously cutting onpositelv facing sides onlv of nonconsecutive teeth, successively. substantially as specified.

5. The procsuof cutting worm-gears of the class described, which consists in rotating the blank from which the worm-gear is to be formed, and successively lcutting only opnositely facing sides of non-consecutive teeth at two separated points by cutters rotating in svnchronism with the rotating blank, and about an axis perpendicular to thc axis of rotation of the blank, substantially as specified.

6. The process of cutting worm-gears nieuwe about an axis perpendicular to the axis of rotation of said blank, substantially as speelied.

. ANDREW BENSON', Witnesses:

JOSEPH HARRIS,

WILLIAM A. GEIGER 

